The output of a conventional power supply circuit using any AC mains power line input, for example, of 115 V AC to 480 V AC, using the voltage regulator of this invention is regulated or limited by the voltage controller to maintain a regulated voltage of limited voltage range to operate a given circuit of halogen lamps or other low voltage incandescent lamps and LED arrays at a constant output voltage in response to load changes and variations in input AC mains power line variations. In the instant invention, an optocoupler is utilized to control input to a step-down transformer and thus the mains power line voltage in conjunction with a feed back loop to control the optocoupler.
In the prior art, the approach to controlling the lamp intensity of halogen lamps often utilizes a step-down transformer of conventional design to reduce input line voltage to a lower required level. Typically, unregulated fluctuation in line voltage in step-down transformers can cause the step-down transformer housing to become hot due to the heat generated by the varying electrical field, thus requiring a large transformer housing to dissipate the generated heat. The unregulated fluctuations in line voltage in conjunction with the unregulated step-down transformer output can cause unregulated light output fluctuations of halogen lamps that can average as much as 50%. The unregulated fluctuations in line voltage and in the power supply output can cause shorter halogen lamp life.
Additionally, the imposition of a fast warm-up of the tungsten filaments of a halogen lamp with high sudden current levels can result in a reduced lamp life.
Methods of regulating sources of direct or alternating current are taught in the prior art. U.S. Pat. No. 2,968,738 to Pintell teaches a circuit for regulating output voltage of an output transformer by altering the conductivity of a resistance element in acordance with a feedback voltage from the output transformer. U.S. Pat. No. 3,267,349 to Krause teaches a low voltage cutoff arrangement for power converters comprising a transistor oscillator coupled through a transformer to a load. The oscillator receives its feedback energy through an auxiliary winding on the transformer. As the voltage level of a DC power source decreases to a predetermined level, a voltage divider arrangement controlling the base electrode of the transistor oscillator causes blocking of the transistor, thereby preventing flow of AC power through a transformer to the load. U.S. Pat. No. 4,017,785 to Perper teaches a power source for fluorescent lamps wherein an oscillator circuit connected across the input terminal of a transformer utilizes a 115 V AC power source rectified to provide a DC input in the order of 150 volts and 20,000 hertz output. An additional winding on the transformer with a rectifier and filter providing a supplemental DC supply connected to the main DC supply supplements a fluctuating main DC supply. U.S. Pat. No. 5,180,952 to Nilssen teaches an electronic track lighting system for low voltage lamps, especially 12 volt halogen lamps, wherein the power supply of 120 V AC of normal power line frequency, 60 hertz, is converted to a high frequency of 30,000 hertz. As a result, the individual step-down transformer required to provide the proper low voltage becomes very small, light and inexpensive, instead of costly, large and heavy units using 120 V/60 hertz voltage supply.
Accordingly, in the prior art it is well-known to utilize a means of reducing line voltage to supply line power (wattage) at a constant voltage. In general, it is known to use a feedback method to control line voltage. However, the combination of the concept of each element of the instant invention, the related use of an optoisolator triac driver and a triac to control energy of an existing mains power supply in combination with a soft start oscillator circuit, a voltage sensing circuit of a feedback pulsing DC voltage and an internal reference pulsing DC voltage oscillator circuit to obtain a regulated AC mains power line voltage output, based upon an; internal reference voltage, within a desired range regardless of variations in input line voltage wherein need for heat dissipation has been reduced because of control of the AC mains power line input current to a power supply, thus enabling related voltage regulator components to run cooler and to be physically smaller in size has not been previously disclosed. The operational advantages of the invented voltage regulator for an AC mains power line regulated power supply comprise a longer halogen or incandescent or LED array life, a soft start lamp operation wherein the lamp filiment exhibits longer life, less heat generation of voltage regulator components resulting from the regulated output of the power supply and consequent down-sizing possible of regulator components.